The present invention relates to organic semiconductors and to the use thereof in organic electronic devices.
Organic semiconductors are being developed for a number of electronic applications of different types. The structure of organic electroluminescent devices (OLEDs) in which these organic semiconductors are employed as functional materials is described, for example, in U.S. Pat. No. 4,539,507, U.S. Pat. No. 5,151,629, EP 0676461 and WO 98/27136. However, further improvements are still necessary before these devices can be used for high-quality and long-lived displays. Thus, in particular, the lifetime and the efficiency of deep-blue-emitting organic electroluminescent devices currently still represent a problem for which there is still a need for improvement. Furthermore, it is necessary for the compounds to have high thermal stability and a high glass-transition temperature and to be sublimable without decomposition. In particular for use at elevated temperature, a high glass-transition temperature is essential in order to achieve long lifetimes.
For fluorescent OLEDs, principally condensed aromatic compounds, in particular anthracene derivatives, are used in accordance with the prior art as host materials, especially for blue-emitting electroluminescent devices, for example 9,10-bis(2-naphthyl)anthracene (U.S. Pat. No. 5,935,721). WO 03/095445 and CN 1362464 disclose 9,10-bis(1-naphthyl)anthracene derivatives for use in OLEDs. Further anthracene derivatives are disclosed in WO 01/076323, in WO 01/021729, in WO 04/013073, in WO 04/018588, in WO 03/087023 or in WO 04/018587. Host materials based on aryl-substituted pyrenes and chrysenes are disclosed in WO 04/016575. For high-quality applications, it is necessary to have improved host materials available.
Thus, there continues to be a demand for improved materials, in particular host materials for fluorescent emitters, especially for blue-fluorescent emitters, which result in good efficiencies and at the same time in long lifetimes in organic electronic devices, lead to reproducible results during production and operation of the device, have a high glass-transition temperature and can be sublimed without decomposition. Further improvements are also necessary in electron-transport materials.
Surprisingly, it has been found that anthracene derivatives which are substituted in the 9-position by a 3-phenanthrenyl group, where both the anthracene and also the phenanthrene may be further substituted, exhibit significant improvements here and are very highly suitable for use in organic electroluminescent devices. These compounds enable an increase in the efficiency and especially in the lifetime of the organic electronic device to be achieved compared with materials in accordance with the prior art. This applies, in particular, to deep-blue-fluorescent devices. Furthermore, these compounds have high thermal stability. In general, these materials are very highly suitable for use in organic electronic devices since they have a high glass-transition temperature. The present invention therefore relates to these materials and to the use thereof in organic electronic devices.
For reasons of clarity, the numbering of the positions of anthracene and phenanthcene is shown below:

JP 2001/332384 claims organic electroluminescent devices which contain phenanthrene derivatives, where the phenanthrene may also be substituted by aromatic groups besides other substituents. However, JP 2001/332384 does not teach that in particular an anthracene to which a 3-phenanthrenyl group is bonded in the 9-position achieves particularly good results in organic electroluminescent devices.
WO 07/123,256 claims in general fluoranthene-9-anthracene compounds for use in organic electroluminescent devices. The anthracene here may also be substituted in the 10-position by further aromatic groups. Besides a large number of other aromatic groups, two structures which contain a 3-phenanthrenyl group on the anthracene in the 10-position are also mentioned. However, the inventive effect of these compounds is attributed to the combination of the fluoranthene unit with the 9-anthracene unit. The presence of the phenanthrenyl group is not accorded any importance.